Lesson #3: Classifying Chemical Reactions II

Summary

Students have learned how to write and correctly balance chemical equations, identify combustion, combination, and decomposition reactions, and recognize characteristics of reactions in order to predict products. Today's focus will be single replacement and the students will perform an experiment to determine a basic activity series of metals. They will be able to compare this series to the known activity series of metals and use this in determining whether a reaction will occur or not. By the end of the lesson the students should be able to predict the products of the single displacement reaction if they are only given the reactants and the activity series. The students will be prepared by the end of today to take a quiz on single replacement the next time class meets.

Objectives

Students will…

Identify a reaction as either combination, decomposition, single replacement, or combustion.
Compare/contrast single replacement with combination, decomposition, and combustion.
Predict whether or not a reaction will occur if given the activity series
Predict the products of combination, decomposition, single replacement, or combustion when reactants are given.
Synthesize an activity series by analyzing the different reactions that occurred (or didn't) in the experiment

Materials

Demo: Mg(s), Zn(NO3)(aq), LiAlO3
Activity Series Lab (attached below)
Lab: well-plates, steel wool pads, magnesium sulfate (0.1M), zinc sulfate (0.1M), cupric sulfate (0.1M), silver nitrate (0.1M), sulfuric acid (0.1M), zinc strips, copper strips, magnesium strips
Homework worksheets (attached below)

Instruction

Opening (10 minutes)

  • Do-Now: Take out homework. Open textbook to pg. 216 and read the section titled Single Replacement Reactions
    • Go over answers to homework worksheet. Worksheet will be displayed on the SmartBoard. I will have a one or two students come up and write in their answers to the HW. If other students did not get the same answers, or the answers are incorrect, we will review and correct the problems.
    • Ask students how their Adopt-a-Chem Rxn Projects are coming along. Any questions/concerns?
    • Explain today's focus: Determining which metals are really reactive and which metals are not very reactive, identifying characteristics of single replacement reactions, predicting products of single replacement reactions
  • Demo: Mg(s) + Zn(NO3) --> Mg(NO3) + Zn(s) versus Mg(s) + LiAlO3 --> no reaction
    • Probing Questions: Why does a reaction occur when magnesium is placed in the first beaker, but not the second?
    • How can we predict whether or not a reaction will occur? (based on reactivity of metals involved)
    • How can we create a list of the reactivity of metals?

Middle (75 minutes)

Activity 1: 60-65 minutes
  • Introduce the experiment: chemicals, lab safety, procedure, data to be collected
    • I will brief the students on the chemicals and their relative safeties. Once they are aware of the chemicals available, I will scaffold their ideas for creating an activity series by asking guiding questions. I will do the same with the data table, so that we end with a useful chart for collecting the data.
    • Students must wear safety googles for this experiment.
    • If we are only given 5 different solutions and 3 different metals, how will we test to see which metal strip is reactive with each solution?
    • How will we record our observations for each type of metal and the result of it's contact with each of the 5 solutions?
    • Will we need to dip the metal strip into the solution that has that metal as its cation? (NO!)
    • Students will work in groups of 2 or 3. They may choose their own lab partner. I will monitor every group's progress as I walk around to each lab station.
Activity 2: If time allows, 5-10 minutes
  • Discussion about activity series lab and its application in single replacement reactions
    • Which metal was the most reactive? How do we know this? Does it readily lose or gain electrons? (Mg, loses and becomes cation)
    • Which metal is the least reactive? How do we know this? Does it readily lose or gain electrons? (Ag, gains and becomes neutral)
    • Discuss trend in activity of nonmetals (decreases as you go down group 7A)
  • Practice a few single-replacement reactions (see textbook for examples)

Closing (5 minutes)

  • Students will hand in their data table and their constructed activity series (informal assessment)
  • Hand out homework: Single-Replacement Reactions Worksheet
  • Remind students to continue working on the Adopt-a-Chem Rxn Project
  • Quiz tomorrow on single replacement- Study!




Notes


Unit Homepage
Next Lesson